Forty-two strains of the silkworm, Bombyx mori (L.), collected from China, Japan, Vietnam, South Korea, Brazil, India, and France were reared in the spring, summer and autumn seasons during 1991–92 at the Regional Station of Central Sericultural Research and Training Institute, Coonoor, Tamilnadu State, India. Analyses were made on five silk yield-contributing characters, namely pupation rate, cocoon weight, shell weight, cocoon shell ratio, and silk filament length. Results indicated the superiority of the following strains for all the above mentioned characters: 14M and JC2P (in spring); NBJPO and JC2P (in summer); and M2, NBJPO and SPJ2 (in autumn). The importance of rearing a given strain of silkworm in the optimal season for its maximum economic value in terms of silk yield is discussed.

Inshell peanuts treated with 10, 14, 18, and 22 ppm cyfluthrin were bioassayed with fifth instar Indianmeal moths, Plodia interpunctella (Hübner) and fifth-instar almond moths, Cadra cautella (Walker), after 0, 2, 4, 6, and 8 months of storage. Emergence of the adult almond moth was greater than Indianmeal moth emergence at residual bioassays of 14, 18, and 22 ppm. Regression of increasing emergence with storage time was significant for the Indianmeal moth at 22 ppm and the almond moth at 14 and 22 ppm. For both species, adult emergence decreased as cyfluthrin concentration increased and was described by quadratic regression.

Larvicidal activity of a congeneric set of N-2-halo- (and 2,6-dihalo) benzoyl-N-phenylureas were determined in in vivo tests against the lesser mealworm, Alphitobius diaperinus (Panzer). Substituent modifications were made in both the benzoyl and anilide portions of the molecule. Linear regression analysis was used to derive quantitative structure-activity relationships (QSAR) from LC₅₀ and LC₉₉ values and a series of physicochemical substituent parameters. The analysis resulted in two significant single parameter regression equations selecting Hammett σ_p constant as the only relevant chemical descriptor and rejecting the other descriptors as insignificant. Penfluron and 2,6-difluoro-N-[[[4-(trifluoromethoxy) phenyl]amino]carbonyl]benzamide were potent larvicides in these tests and exceeded the effectiveness of diflubenzuron and triflumuron.

Studies were conducted in the laboratory and in growth chambers to determine if the location of particular seeds within soybean pods were preferred by adult Nezara viridula (L.), Euschistus heros (F.), and Piezodorus guildinii (Westwood) (Heteroptera: Pentatomidae). Results demonstrated that feeding frequency, as indicated by the number of punctures (i.e., stylet sheaths), was significantly greater (P < 0.05) on the proximal seed, than on other seeds, both for detached pods and pods on plants. In general, the number of punctures on the proximal seed was 2–3X greater than punctures observed in the medial or distal region. Of the three species studied, N. viridula showed the greatest feeding activity and P. guildinii the least. No significant differences in feeding activity between sexes were observed. N. viridula fed more frequently at 22 than at 29°C, while no significant temperature effect was observed for E. heros.

Bemisia tabaci (Gennadius) is the most important vector of viruses which cause diseases of “serrano” pepper in southern Tamaulipas, Mexico. This insect is highly attracted to yellow surfaces. When 1,240 yellow traps/ha were uniformly placed in plots, plants with virus symptoms were reduced 61%, 59%, and 15% in 1987/1988, 1988/1989, and 1990/1991, respectively, on the last sampling date yet there was no significant difference in treated and untreated plots. In plots without treatment 78, 91, and 100% of plants exhibit virus symptoms on the last sampling date in the same years, respectively. Plots with traps increased yields of peppers 539%, 202%, and 341% in 1987/1988, 1988/1989, and 1990/1991, respectively, compared to the check. Traps + permethrin at 110 g (AI)/ha reduced populations of B. tabaci adults 78% in the 1987/1988. Permethrin-treated plots without traps increased yields 312% and 366% compared to the control in 1988/1989 and 1990/1991 seasons, respectively. During these same years yield increases were greater than the untreated check when Lambda cyhalothrin, cypermethrin, phosphamidon, dimethoate, naled, Safer^™ soap, amitraz, and endosulfan were applied in the same tests.

Genetic variation among 14 populations of Dioryctria disclusa Heinrich adults was examined using starch gel electophoresis. The average number of alleles per locus exceeded 2.0 in all populations. The number of polymorphic loci exceeded 70% in 11 populations. Genetic structure data suggest moderate differentiation (average F_st, 0.111) among the populations. Most of the differentiation is attributable to three of the eight loci (MDH, ME, and IDH). Nei's genetic identity ranged from 0.77–1.00 between populations. A phenogram based on genetic identity and unweighted pair-group method of analysis (UPGMA) clustered five of six populations in North Carolina closely together. With a cophenetic correlation of 0.96 the phenogram constructed is acceptable.

The accessory reproductive glands of the female stable fly are translucent structures that run parallel to the common oviduct when the ovipositor is extended. The only muscles found associated with the gland were those at either end of the long tube of simple cuboidal epithelial cells. The posterior region of each gland is connected to the anterior vagina by means of a valve of circular muscle. The myofibrils of the valve are separated into sarcomeres of irregular alignment with Z disks that appear as discontinuous rows of dense bodies. Transections through the Z disk region also revealed a perforated character which is common in muscles that have the ability to super contract. The sarcolemma of many cells have tubular invaginations that correspond to the T-system of tubules found in most muscles. Terminal axons with both synaptic vesicles and larger neurosecretory granules were found in close apposition to muscle fibers of the valve. Large vacuoles (with a mean of 26.36 μm and a SD = ± 2.09) were the most prominent structures in the cytoplasm of the glandular epithelium. The fine structure of these vacuoles showed a microvillar border and a central portion that contains clumps of secretory material in a granular matrix. Many vacuoles also contain dense inclusion bodies while other inclusion bodies were observed in apical membranous networks just beneath the cuticular intima. Such ultrastructural features suggest a largely merocrine type secretion for this gland.

Ground-applied treatments of two commercial Bacillus thuringiensis subsp. kurstaki formulations (MVP and Dipel ES) and tank-mixes with a pyrethroid (Ambush 2E) were evaluated for control of European corn borer, Ostrinia nubilalis (Hübner), larvae in sweet corn. Treatments were applied at average intervals of 3.4, 5, 7, and 10 days to determine field persistence. Manual infestations of first-instar O. nubilalis were used to augment natural populations. During both years, there were no significant interactions between application interval and treatment for all dependent variables tested, including late instars per ear, percent marketability, yield, and predator density. Regardless of application interval, MVP provided greater larval control than Dipel ES. However, the decline in efficacy of the encapsulated MVP formulation occurred at the same rate as that of the non-encapsulated Dipel ES formulation over the 3.4 to 10-d intervals. Tank-mixes of B. thuringiensis + low-rate permethrin provided no additional control compared with low-rate permethrin alone. Given the infestation levels present in this test, neither B. thuringiensis formulation provided control sufficient to maintain current processor standards of 5–10% infested ears at harvest.

Microplitis croceipes (Cresson) and Cardiochiles nigriceps Vierick, parasitoids of Heliothis virescens (F.), were treated topically with field rates of 14 formulated insecticides commonly used in cotton insect control. The 14 insecticides were oxamyl, thiodicarb, endosulfan, acephate, azinphosmethyl, chlorpyrifos, dicrotophos, dimethoate, methyl parathion, profenofos, bifenthrin, cyhalothrin, cyfluthrin, and cypermethrin. With the exception of thiodicarb, all insecticides were extremely toxic to M. croceipes, causing 100% mortality of adult wasps. Treatment with thiodicarb resulted in high survival of adults for each parasitoid species. Acephate was extremely toxic to M. croceipes, but relatively non-toxic to C. nigriceps. Mortality also was lower for C. nigriceps females than for C. nigriceps males and M. croceipes for both sexes when wasps were treated with oxamyl. Nine of the 14 insecticides tested were extremely toxic to C. nigriceps, causing 100% mortality of adult wasps. Treatment with 5 insecticides - thiodicarb, acephate, oxamyl, azinphosmethyl, and cypermethrin - resulted in higher survival for C. nigriceps adults than was obtained for the other nine insecticide treatments. For both male and female C. nigriceps, thiodicarb and acephate were less toxic than the other three insecticides. Generally, these five insecticides were less toxic to females than males. An exception was the lower mortality of male C. nigriceps versus females of this species for treatment with acephate. Of the three insecticides commonly used for boll weevil control (oxamyl, azinphosmethyl, and methyl parathion), oxamyl was the least toxic to C. nigriceps females. Cypermethrin was less toxic to C. nigriceps females than the other three pyrethroids tested. Selective use of insecticides which permit higher parasitoid survival could facilitate conservation of these native biological control agents.

Soft red winter wheat (27.27 kg replicates) treated with combinations of deltamethrin + chlorpyrifos-methyl, with and without piperonyl butoxide, and cyfluthrin, applied alone or with either chlorpyrifos-methyl or piperonyl butoxide, was stored from 15 May 1992 to 9 February 1993 (6 chemical treatments and an untreated control). Each replicate was artificially infested with 50 adult lesser grain borers, Rhyzopertha dominica (Fab.), and 50 adult rice weevils, Sitophilus oryzae (L.), upon initial storage, sampled with probe traps at monthly intervals, and subsequently reinfested. Trap catch of lesser grain borer was always 0, except for two traps at month 4 that contained one adult in each trap. Maximum population levels of rice weevil and a natural infestation of the red flour beetle, Tribolium castaneum (Herbst), occurred at month 5. Trap catch of these two species in the chemical treatments averaged 2.2 to 34.0 and 0.0 to 19.5 live adults per trap, respectively. From months 4 to 9, the percentage of insect-damaged kernels averaged 4.0 to 5.5% in wheat treated with 0.25 ppm deltamethrin + 6.0 ppm chlorpyrifos-methyl + 4.0 ppm piperonyl butoxide. Maximum kernel damage in the other chemical treatments was 3.2%.

Five species of parasitoids of larval stalkborer were evaluated in Texas in 1987 against the Mexican rice borer, Eoreuma loftini (Dyar), in field enclosures in rice, Oryza sativa L. The braconids, Alabagrus stigma (Brullé) and Allorhogas pyralophagus Marsh, and the bethylid, Goniozus natalensis Gordh, each parasitized >5% of the available E. loftini. The braconids, Apanteles minator Muesebeck and Macrocentrus prolificus Wharton, parasitized <1% of the available hosts. Allorhogas pyralophagus parasitized the highest percentage of borers, including 65.6% of the fifth- and sixth-instar E. loftini. Alabagrus stigma and G. natalensis parasitized fewer borers overall, although parasitism by A. stigma averaged 21.2% of small E. loftini in the rice leafsheaths. Alabagrus stigma, A. pyralophagus, and G. natalensis are candidates for further evaluation in the event that E. loftini becomes a pest of rice in Texas.